I think I understand your question. You want to be able to play slurred notes that are "connected" and smooth even though the interval between the notes is great. If this is correct, I have two ideas that might help. One is to practice slurring the tones of a scale with this pattern:
Do-Re-Do-Mi-Do-Fa-Do-Sol-Do-La-Do-Ti-Do-Do-Do
Do it slowly and as the interval increases, try to make the notes as connected as the previous interval. Work until you can make the octave as smooth and connected as the major second. It is very important that the finger movements be very quick and precise, even though the notes are long tones. It is also very helpful to increase the speed of the airstream as the notes go higher and higher. Think of "blowing into" the higher of the two tones.
Another excellent way to develop airstream control and the concept for playing connected phrases is to blow the pitches of the melody on an "air whistle" (not a true whistle, but the air makes a pitch). Do this a few times and then play the melody on your saxophone using the same airstream. Good luck. Hope some of this helps.
John
